cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A103801 Indices n such that A019565(n)+/-2 are both primes.

Original entry on oeis.org

4, 6, 10, 14, 22, 26, 34, 38, 62, 78, 106, 138, 142, 162, 190, 194, 230, 258, 274, 278, 302, 402, 430, 458, 494, 498, 534, 550, 618, 670, 674, 690, 694, 742, 770, 814, 822, 902, 934, 1014, 1030, 1038, 1062, 1090, 1102, 1106, 1142, 1146, 1182, 1222, 1234
Offset: 1

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Author

Lei Zhou, Feb 22 2005

Keywords

Examples

			A019565(4)=5, 3 and 7 are both primes, so a(1)=4;
A019565(6)=15, 13 and 17 are both primes, so a(2)=6;
		

Crossrefs

Programs

  • Mathematica
    A019565 = Function[tn, k1 = tn; o = 1; tt = 1; While[k1 > 0, k2 = Mod[k1, 2]; If[k2 == 1, tt = tt*Prime[o]]; k1 = (k1 - k2)/2; o = o + 1]; tt]; Do[cp1 = A019565[n] - 2; cp2 = cp1 + 4; If[PrimeQ[cp1] && PrimeQ[cp2], Print[n]], {n, 0, 20000}]
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